Not applicable.
The present invention relates to solid fuel compositions, and, in particular, to a solid fuel composition useful for manufacturing an artificial fire-log. The solid fuel composition is made from a combination of a coffee-waste component and sawdust together with a combustible wax binder, to produce better flame output and sounds similar to a natural wood log as it is burned.
Manufactured fire-logs are becoming an increasingly popular choice as a fireplace fuel for enjoying a convenient, attractive, cost-effective fire. Typically, manufactured fire-logs provide a consistent flame for a reasonably long period of time, with little effort required to light or maintain the fire. With the rising cost of wood, manufactured fire-logs represent a cost-effective alternative to natural wood fires. Manufactured fire-logs also advantageously consume materials that might otherwise end up in landfill sites.
U.S. Pat. Nos. 5,910,454 and 6,113,662, which issued to the Applicant in 1998 and 2000, respectively, disclose that spent coffee grounds make an ideal fuel component for solid fuel compositions. Spent coffee grounds have a higher calorific value and a higher volatile to fixed carbon ratio than wood. Thus, it has been demonstrated that it is possible to make a fire-log using a major proportion of spent coffee grounds and as little as 35% wax that is equivalent in flame output to that of a fire-log made with sawdust and over 60% wax.
As fire-logs have grown in popularity, consumers have developed an interest in more xe2x80x9cnatural burningxe2x80x9d fire-logs which simulate a natural wood fire. For example, U.S. Pat. Nos. 5,118,539, 5,868,804, and 6,017,373 each teach that by adding seeds and other artificial additives, it is possible to simulate the xe2x80x9ccrackling soundxe2x80x9d of a natural wood fire. U.S. Pat. No. 6,017,373 teaches that inclusion of moist sawdust served to enhance the crackling sound, but was not sufficient to cause it. While fire-logs that incorporate seeds or the like do provide a xe2x80x9cpopping soundxe2x80x9d, the sound lacks the xe2x80x9csizzlingxe2x80x9d sound of wood and the irregularity of the burn and sound pattern of a natural wood fire. Besides, the addition of such seeds, even in relatively small amounts, contributes to the cost of the fire-logs because the seeds are relatively expensive.
Consumers are also demanding fire-logs that provide a higher flame output. Fire-logs on the market today usually contain the maximum wax content that the solid particulate can support. Many also include a coking agent to permit the addition of more wax than the solid particulate alone can support. The coking agent, generally a sugar or molasses additive, coats the fire-log as it burns to retard the evaporation rate of the combustible wax, and to hold the fire-log together. Although effective, coking agents also contribute to the cost of a fire log.
Consequently, there exists a need for an inexpensive manufactured fire-log that has good flame output and also burns with a crackling sound similar to the sound of a natural wood fire.
It is therefore an object of this invention to provide a fuel composition that provides a maximum safe flame output suitable for combustion in a fireplace without the use of a coking agent.
It is another object of the invention to provide a fuel composition that burns with a sizzling and crackling sound similar to the sound of a natural wood fire.
The invention therefore provides a processed solid fuel composition comprising a combination of spent coffee grounds and/or green coffee bean waste, sawdust and a combustible wax binder. It has been established that spent coffee grounds and/or green coffee bean waste in as little as 1% and as much as 50% by weight of the composition produce an added benefit of improved flame and sound output in a sawdust/wax fire-log. This combination of solid particulate combined with the wax binder provides natural sizzling and crackling when it is burned. The spent coffee grounds and/or green coffee bean waste also promote surface cracking of the solid fuel composition as it combusts. The surface cracking of the solid fuel composition increases surface area exposed to combustion air, and thereby enhances flame output.
It has also been established that high moisture coffee-waste can be added to the fuel composition in effective quantities without noticeably affecting the flame output or reducing the sound output. This permits at least a proportion of the coffee-waste to be used in the condition in which is received from a waste facility. Drying energy and costs are therefore reduced.
For best sound output, the coffee-waste particles are preferably at least about 0.5 mm in diameter. Finer particles can be agglomerated in wax or pelleted to increase particle size before they are incorporated into the solid fuel composition in accordance with the invention.